Classification of valvular heart disease
Generally, can be classified as either:
Stenotic valvular disease
Valves are narrowed causing increased resistance to forward blood flow almost always due to a disease process of the valve itself.
Regurgitant valvular disease
Incompetence of the valve causing increase in backward blood flow. This occurs either with a primary valve abnormality or an abnormality of the surrounding structures e.g. aortic root dilatation, papillary muscle rupture etc leading to a functional regurgitation.
Causes of valvular disease
The causes of valvular disease may be congenital or acquired (different valves affected differently). The mitral and aortic valve are affected most commonly.
Most common types of valvular disease
Acquired stenosis of the aortic and mitral valves accounts for 2/3 cases of valvular disease
Calcific aortic stenosis causes
Usually a consequence of age-associated wear and tear and chronic injury due to hperlipidemia, HTN, inflammation and other risk factors for atherosclerosis - cause deposition of the calcium salt hydroxyapatite.
Risk factors include:
- Increasing age
- Congenital bicuspid valve (1% of population, usually asymptomatic, predisposed to progressive degenerative calcification (usually have unequally sized cusp, the larger with a midline raphe)) and present at 50-70 years of age.
- Chronic injury contributes to the aortic valve calcification of hydroxyapitite which is the same calcium salt that is found in bone.
Macroscopic appearance of calcific aortic stenosis
Heaped up calcified masses within the aortic cusps that protrude through the outflow surfaces that ultimately distort the cuspal architecture and prevent the opening of the cusps. Commissural fusion is not usually seen.
Microscopic appearance of calcified aortic stenosis
Calcific process in the valvular fibrosis at the points of maximal cusp flexion.
Clinical presentation of calcific aortic stenosis
- Mid-systolic ejection murmur
- Heart failure secondary to pressure overload
Definitely need a valve replacement once symptomatic.
Myxomatous degeneration of the mitral valve
One or both mitral valve leaflets become floppy. Unknown aetiology. Estimated to affect up to 3% of the population in the United States. Often affects young women.
Macroscopic appearance of myxomatous degeneration of the mitral valve.
Intercordal balooning of the mitral leaflets that are often enlarged, thick and rubbery. Annular dilation and elongated thinned tendinous cords that can occasionally rupture.
Microscopic appearance of myxomatous degeneration of the mitral valve
Attentuation of collagenous fibrosa layer and thickening of sponsiosa layer with (mucoid) myxomatous material.
Complications of myxomatous degenration of the mitral valve